[Morthoron]

Hmmmm....off the top of my head (and not looking at most of the thread):

Gandalf, of course, would ride an Eagle (originally AMC, then Chrysler).
Aragorn would choose a Ranger (pick-up) or a Pathfinder (Nissan).
Bard would prefer a black Arrow (Pierce-Arrow).
I suppose Fangorn would need a Forester (Subaru).
Cost-conscious Hobbits might choose a Midget (MG).
Orcs probably tool around in Gremlins (AMC).
Tooks or Brandybucks might opt for a Country Squire (Ford).
Earendel sits back in a Grand Voyager (Chrysler).
The Maia Tilion probably has an Eclipse (Mitsubishi).
Gil-Galad has a Javelin (AMC).
I can imagine the Mouth of Sauron with an Envoy or Ambassador.
Barrow Wights? Wouldn't they love a Ghost (Rolls-Royce)?
The Nazgul all drive Phantoms (Rolls-Royce).
Grima Wormtongue might select a Protégé (Mazda).
Shelob goes to market in a Spider (Toyota).

And, of course, Elrond's car dealership of choice is Ford of Bruinen.